How to set up HDRI environment in Corona for 3ds Max?

Environment HDRI lighting tutorial

To use an HDR bitmap as the environment for your scene:

Method 1 - 3ds Max Environment

• Make sure you have CoronaRenderer set as the render engine in Render Settings.

1. Open Environment and Effects menu. In 3ds Max press 8 or go to Rendering > Environment.... Environment and Effects menu will show up.

2. Open the Slate Material Editor. If the Editor is not in Slate mode, Select Slate Material Editor in the Editor's Modes menu.

3. In the left side of Material Editor, under Maps > Corona drag-and-drop CoronaBitmap into the editor. A window for loading a bitmap will pop up.

Locate and Open (double click on) your HDRI. 

Press OK.

4. Make sure that in CoronaBitmap's parameters, under "Environment Mapping" rollout, "mode" dropdown is set to what corresponds to your HDRI's mapping (Spherical, Cross etc.). Most of the HDRIs have Spherical mapping, which is set by default.

5. Drag from CoronaBitmap's end into Environment Map's None slot. Make sure None slot is visible before doing this, as Material Editor will come over any other window while dragging. 

In popped up window pick Instance and press OK.

From now on, your HDR loaded in CoronaBitmap will be used both as the background for your Scene (maybe also for viewport) and to generate lighting.

Method 2 - Corona Environment

Alternatively, you can go to Render Setup > Scene > Scene Environment and under "Scene environment" switch from "Use 3ds max settings (Environment tab)" to "Single map". Then load your bitmap into Corona's environment slot. With this setup, the map in 3ds Max's environment slot will be ignored. There is no performance or quality difference between these two setups.

Environment Overrides

If you want to use HDR bitmaps as overrides, you can put them respectively in "Direct visibility override", "Reflections override" or "Refractions override".

Different maps in different override slots:

Result of using these overrides:

Excluding Objects from Environment Illumination

Starting from Corona 12, you have the ability to exclude specific objects from environment illumination. This feature can be found in the Render Setup > Scene > Scene Environment section. 

To use this feature:

1. Open the Render Setup dialog and navigate to Scene > Scene Environment.
2. In the Scene Environment section, you'll find a new dropdown menu labeled "0 objects excluded...".
3. To exclude objects from environment illumination:
   • Select the objects in your scene that you want to exclude.
   • Click the "+" button next to the dropdown to add them to the exclusion list.
4. You can use the dropdown menu to review or modify your selection of excluded objects at any time.
5. "Accurate sampling (slower)" checkbox: This option enables more precise sampling of environment maps. While slower, it provides more accurate results for highly detailed maps. This can sharpen lighting and shadows from environment maps, particularly for small light sources like the sun in the map. Enable this if you notice flickering in the lighting.

Excluding objects from environment illumination in Corona 12.

Per-Material Environment Overrides

You can also use HDR bitmaps as reflection or refraction overrides for each material. To do this, go to your Corona material and load your HDR bitmap into the material's "Reflect BG override" or "Refract BG override".

In a Corona Physical Material, use the corresponding Refl. env. and Refr. env. inputs.

Result of using different overrides for different objects:

Per-Camera Environment Overrides

You can override the environment map(s) per-camera:

 

The above examples come from a single scene. Left - a camera using a forest HDRI as the scene environment with a reflection override enabled so that there are no tree reflections in the water. Right - another camera using a daylight HDRI as the scene environment and an evening HDRI as the reflection override.